Sensitive information from a nuclear power plant in Ukraine was exposed due to an illegal cryptocurrency mining operation run by workers, according to several media reports.

Local media reported that the Security Service of Ukraine (SBU) last month discovered unauthorized computer equipment at the South Ukraine Nuclear Power Station near the city of Yuzhnoukrainsk in the Mykolaiv province.

Investigators found that workers, possibly with assistance from some of the National Guard troops that protected the facility, were running a cryptocurrency mining operation. They were not using plant equipment — they took their own mining rigs into an administrative building — but they were using the organization’s electricity network to power their devices.

Cryptocurrency mining equipment requires a lot of power and entities involved in these types of activities often look for locations with inexpensive electricity.

In addition to stealing electricity from the power plant, the individuals responsible for the operation connected their equipment to the organization’s intranet and to the internet, which reportedly led to the exposure of classified information about the facility’s physical security. This type of information is said to represent a state secret.

Investigators uncovered video cards, switches, storage devices, power supplies, motherboards, and cables and other accessories in the room from where the operation was run.

Phil Neray, VP of Industrial Cybersecurity at CyberX, told SecurityWeek that the operation likely went undetected for months or even longer, exposing critical infrastructure to “potentially catastrophic safety issues.”

“This is a great example of 'trust but verify' -- even with the strictest policies and regulations in the world, it's all theoretical if you aren't continuously monitoring for unusual or unauthorized activity,” Neray said.

Incidents where employees of organizations in the nuclear sector have abused their privileges to mine for cryptocurrencies are not unheard of. Last year, engineers at the Russian Federation Nuclear Center were arrested for using one of the organization’s supercomputers to mine bitcoin.

Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.